Stereoselective synthesis of 5-alkyliden-6-aminotetrahydro-2-pyranones through an unexpected isomerization of the hydroxytetrahydro-2-pyridinones obtained by the selective reduction of acylated enaminones

摘要

A convenient methodology for the stereoselective preparation of 5-alkyliden-6-aminotetrahydro-2-pyranone 4 is reported. The synthesis of 2-pyranone 4 occurs through an unknown isomerization mechanism of the hydroxytetrahydro-2-pyridinone 3, an accessible starling material obtained by mild and selective reduction of the 5-acyltetrahydro-2-pyridinone 2. The isomerization mechanism and the stereoselectivity in the synthesis of 2-pyranone 4 was investigated and rationalized. (C) 1997 Elsevier Science Ltd. All rights reserved. [References: 24]